The invention relates to a method by which, in a computer-assisted manner, machine components can be determined that are particularly suitable for a specified use.
“Machine components” are understood below to mean individual machine elements or groups of interacting machine elements that are combined to form specific aggregates. Each machine element considered is a very small technical functional unit that is suitable for fulfilling the technically functional requirements arising from each technical use considered. The term “machine component” accordingly also encompasses the parts, raw materials or process parameters applied in the manufacture of machine components or their machine elements since the properties and functions of the components and elements considered here are always characterised by the manner in which they are manufactured and the materials and methods used for this.
Currently, machine components are generally designed according to standardised methods with respect to the respective use. This approach is simple, proven, and safe because it secures individual differences in the uses through generalised “safety factors”.
This selection and design system is described in more detail, for example, in “Maschinenelemente 2, Prof. Schlecht”, Addison-Wesley Verlag; 2nd edition (1 Nov. 2009), ISBN-13: 978-3827371461, or “Maschinenelemente, Roloff/Matek” Springer Vieweg; 21st edition, fully revised 2013 edition (9 Aug. 2013), ISBN-13: 978-3658023263.
A typical example of machine components that can be selected in the manner considered and newly presented here is belts for belt drives. The selection of such belts is usually made in accordance with the VDI guideline 2758 “Riemengetriebe” of June 1993.
The conventional procedure for the use-specific selection of such machine elements from machine elements supplied as in a catalogue, in particular manufactured according to a specific manufacturer specification, can be summarised as follows (see also enclosed FIG. 2).    (a) The conditions set by the intended use and to be considered in the selection of the machine element are ascertained. These conditions include, for example, the static and dynamic loads to which the machine element will be subject during operation, as well as external conditions such as ambient atmosphere, temperatures, friction pairs, machine concept, etc. under which the machine element is to be used.    (b) Taking into account the machine concept, the engineer specifies a certain type of machine element.    (c) c.1 For the machine element type specified in (b), the performance values to be generated by this machine element type are calculated based on the conditions to be considered (a).            c.2 The calculated performance values are assigned safety margins in order to secure inaccuracies in the performance value calculation (b) or unforeseeable uncertainties occurring in practical use.            (d) On the basis of the performance values assigned safety margins, the machine element suitable for the intended use is selected from the machine elements supplied as in a catalogue.
Work steps (c) and (d) are usually depicted by tables or diagrams, or alternatively also by suitable software by means of which, based on the conditions (a) to be considered and in accordance with the decision taken in step b), the performance values to be generated in each case by the relevant machine element can be determined.
This design methodology, which is appropriate for practice but based on comparatively rough estimates, has the following limitations and disadvantages:                A preliminary specification of a particular machine element type is made.        In the further design and selection of the suitable machine element, the view is accordingly restricted to this one machine element type. Alternative machine elements that would possibly better solve the particular drive task within the framework of the predetermined machine concept are no longer taken into account in the further consideration subsequent to the preliminary specification.        The expected service life of the particular machine element cannot be taken into account in the selection and design, since the selection is secured by such high safety factors that the theoretically achievable service life of the machine element is much higher than the service life required or desired in practice.        In general, the machine element is more precisely determined and designed depending on fewer influence quantities. Consideration of a plurality of different but mutually dependent or influencing selection criteria is generally not possible due to the associated computing time.        The concrete design of the selected machine element is generally performed without consideration for the influence quantities related to the use. At best, such influence quantities are included in a roughly generalised manner.        The design is always carried out with very high safety coefficients in order to cover, with sufficient certainty, influence quantities that are unknown or not considered in detail.        The overdimensioning occurring as a result of the generalisation and safeguarding by means of safety margins leads to an unnecessary increase in the price of the particular machine element.        The capabilities of the machine elements are not used optimally. Due to the generalisation and safeguarding by means of safety margins, solutions that could be used with great success in practice are not feasible.        
With regard to a use in which drive forces are to be transmitted to a part to be moved, this means that the engineer first specifies, for example, “belts” as their chosen traction mechanism. As a result, in their further considerations, they no longer commit to alternative traction mechanisms or drives that would possibly better solve the driving task.
The design of endless toothed belts is then carried out based on performance values that are stated in catalogues and that the belt manufacturers publish in general terms, that is, not use-specifically. The details supplied by various manufacturers relating to the drive belts they offer are not comparable because it is not clear on which basis the details have been determined. In particular, it is not known on which service life basis the values have been determined. Detailed guidelines or standards on how comparable performance values can be determined do not currently exist. Instead, the manufacturers of drive belts define their own calculation and design methods. As a result, the properties and selection criteria indicated by the different manufacturers are not comparable, or at most can only be compared with substantial effort and considerable uncertainty. Thus, products with seemingly similar property profiles often prove not to be mutually interchangeable because the stated properties have been determined in different ways.
A rough guideline for the calculation of the requirements that drive belts must fulfil is given in the guideline VDI 2758. Section 3 states: “The belt drive must on the one hand work safely under the specified requirements or operating conditions (rotational speeds, torques, space requirements, overloads, shaft displacements, temperatures and other environmental influences) over a reasonable period of time and should on the other hand minimise the environmental impact (noise, vibrations, etc.).” The question as to how these requirements can be fulfilled whilst ensuring optimal utilisation of the performance potential provided by the drive belt remains open.